External contracting brake



Aug. 7, 1928. 1,679,991

H. A. SCHWAGER EXTERNAL CONTRACTING BRAKE Filed Feb. 5, 1927 Patented Aug. 7, 1928.

HENRY A. sonwnenn,

CORPORATION, OF

DE ROYAL OAK, ZNITCHIGAIN' ASSIGNOR TO GENERAL MCI'IFOBS DETROIT, MICHIGAN} A CORPORATION OF DELAWARE.

EXTERNAL CONTRACTINGBRLL'KE.

Application filed February This invention relates to brakes; to the type of brake employing a band and a drum, there being a relative rotation between these two parts.

The improved brake has been pell er shaft.

The invention however is not limited to vehicles and may be advantageously employed where ever a band brake 1S tound to be of use.

The object of the invention is to make an improved band brake wherein the band sections wear uniformly over the entire periphery and wherem the clearance 18 at all times uniform.

Other objects and advantages will be understood after reading the following specification. Accompanying the specification is a drawing illustrating what is now believed to be the preferred form of the invention.

The single figure shown in the drawing is a side elevation of an external contracting brake embodying my invention.

Referring by reference characters to the drawing, numeral 3 represents a fixed plate.

This plate, 111 the case of a vehicle brake,

may be the dust g axle. may be mounted uard carried on the vehicle Numeral 5 represents the drum which on the vehicle wheel. Surrounding the drum is a brake band 7 having the usual brake lining 9.

is fastened at 11 To the fixed plate an anchor 13. This anchor is straddled by a U-shaped member 15 fastened by rivets 17 to the brake band 7. Suit able adjusting means are shown at 19.

Between the adjacent ends of the band is a guide 21 secured to the fixed plate by "fastening means 23. The guide 21 has an apertured projection 25 through which passes a rod 27.

The rod 27 is pivoted at 29 to a fitting 31 carried by one end of the brake band. A

similar fitting 33 is riveted to the other end of the band and to this fitting is pivoted at 35 one end of a eonvcntional operating lever 37, The other end oi the operating lever 1s apertured as at 39 or otherwlse formed for attachment to an operating rod not shown. The lever 37 is apertured at through apertur outer end of the at 4.1 and upon an. intermediate point and e the rod 27 extends. The rod 27 is threaded as shown this threaded end is adjust- 5, 1927. Serial no. 166,234.

Surrounding rod 27 are two sprlngs 45 and 47 thesetwo springs having their adjacent ends in abutment with opposite faces with projection 25. The remote end of spring 17 engages a suitable seat on rod 27. The remote end of spring 45 is seated against lever 37 on the side of the latter opposite that engaged by nut 1-3.

From the construction described it will be understood that the action of the lever 37 and the springs 45 and t7 applies the two sections of the brake band to the drum through the agency of the coil springs which are so equalized that the tension upon both is the same. If the two springs are-of the same length the brake would operate satisfactorily provided the band sections, the parts on each side of the anchor, were equal. It is common practice however to locate the anchor off centre so that the longer part of the band is self-actuating in the forward direction of travel. It should be kept in mind that equal pressures on springs of equal length will compress the springs to equal. extents. It will then be clear that with such equal springs the movement of the two ends of the band will be the same and the longer band would not be drawn so closely about the drum as the shorter band for a given pedal pressure. It is known, however, that in the case of several springs the deflection for a given load is proportional to the number of coils. Iftherefore, springs 45 and L7 be given a number of coils proportional to the length of the respective sections of the brake band a given force applied to the brake will deflect the springs to unequal extents and in each case the extent of the deflection will be proportional to the length of the band sections, and will also be proportional of course to the extent of a floating abutment anchor dividing ratio as the lengths of the band section.

'2. In a band brake, a drum, a band, an the band into unequal sections, a leverfor applying the band sections to the drum, coil springs associated with said lever to release the band, the number of eoils in the coil springs being in the same ratio as the lengths of the band sections. 3. In a brake, a drum, a band having unequal sections, a fixe guide between the ad- ]acent ends of the band, a lever pivoted to I one of'said adjacent. ends, a rod pivoted to the other adjacent end, said lever having a part movable on said rod, a spring between said guide and one end of said band, another spring between said guide and said lever, means on said rod to adjustably engage said lever under the action of said second spring, the lengths of the two springs being proportional to the lengths of the two sections of the band While under equal pressure.

4. In a brake, a drum, a brake member for frictional engagement with said drum, said brake member being constituted by parts of unequal length, anchoring means for said brake member, means including a lever for applying the parts of brake member to the drum, and springs associated with said lever to release said brake member, the deflections of the springs under equal loads being in the same ratio as the lengths of the parts of the brake member.

In testimony whereof I affix my signature.

HENRY A. SCHWAGER. 

